1. Field of the Invention
The present invention relates to a needle that pierces an elastic body, which is stopping a flow passage, so as to interconnect regions of the passage, which are separated by the elastic body; and also to a manufacturing method of the needle.
2. Description of Related Art
JP-A-2005-14437 discloses an ink cartridge having an ink bag to be filled with ink, and an image formation apparatus including therein the ink cartridge. The ink cartridge includes a supporting member thermally bonded to the ink bag. An ink inlet and an ink outlet are formed in the supporting member. An elastic body made of rubber is provided at an end of the ink outlet to tightly seal the ink outlet. The ink inlet is sealed by heat after the ink bag is filled with ink introduced through the ink inlet. The ink bag is thus kept in a state of being filled with ink. A hollow needle is provided in a main body of the image formation apparatus to introduce ink into the main body. The needle is formed into a tube having therein an ink introducing passage. A front end portion of the needle is tapered, and an ink introducing hole is formed on a side face of the front end portion. By sticking the needle into the elastic body of the ink cartridge, the ink introducing passage of the needle is connected through the ink introducing hole with the ink outlet of the supporting member, and thereby ink in the ink bag is supplied into the main body of the image formation apparatus.
In the above-described technique, when the needle is stuck in the elastic body, the elastic body enters, by its elastic restoring force, the ink introducing hole of the needle. When the needle is moved till its ink introducing hole, in which the elastic body has entered, reaches the ink outlet of the supporting member, a shear force is applied to the elastic body by the peripheral edge of the ink introducing hole of the needle so that the elastic body is scraped off. Scraped-off pieces of the elastic body are sent together with ink in the ink bag through the ink introducing hole of the needle into the main body of the image formation apparatus. The pieces of the elastic body cause an ink ejection trouble in an inkjet head.